Too soon? With Avengers: Infinity War still in cinemas, the world is hardly screaming out for another effects-laden saga of superheroes banding together to defeat a baddie played by Josh Brolin. But Deadpool is in a different league – or at least a different age rating. Where most superhero movies have gone family and broad, Deadpool went adult and rude, and revelled in the possibilities a UK 15 or US R rating opened up in terms of “strong bloody violence”, “strong language” and “crude depictions of sexual acts”, to quote the British Board of Film Classification. Not to mention a generation’s worth of pop-culture references only an older audience would appreciate. The gamble paid off handsomely: Deadpool became the second highest grossing R-rated movie in US history after The Passion of the Christ. And that audience will need little persuasion to return for the sequel – just the mention of a running gag about Barbra Streisand’s Yentl will probably be enough. But now that there’s a lot riding on it, this sequel is presented with a challenge: how to send up the genre without looking as if you are part of it?

What made the first Deadpool, and saves this one, is the way they mix emotional sincerity in with the meta-movie wisecracking. The comedy comes from a place of pain, and Ryan Reynolds’ ability to flip between both registers so effortlessly is a superpower few actors possess. Thus, this second instalment begins with Reynolds’ Deadpool attempting to kill himself. Given his capacity for regeneration, he fails, of course. After a few hilariously gory fight scenes and another Bond-movie parody title sequence, it’s explained how it came to this: Deadpool has become tragically separated from his true love Vanessa (Morena Baccarin). His relationship with his “surrogate family”, the X-Men, also gets off to a bad start when they team up to confront a teenage mutant Kiwi firestarter named Russell – played by Julian Dennison, the kid from Hunt for the Wilderpeople. On the trail of Russell, for reasons initially unknown, is Brolin’s mean, tooled-up cyborg soldier Cable, who doesn’t need an Infinity Stone to travel back in time. “You’re so dark. Are you sure you’re not from the DC universe?” asks Deadpool.

Snappy, self-aware, fourth-wall-breaking lines like that flow fast and rarely miss their targets in the ensuing adventure. The lines between good guys and bad guys are refreshingly blurred, and the movie is at its funniest when it genuinely subverts the formula – as with Deadpool’s ill-prepared attempt to assemble his own “X Force” superhero team. But there are still boxes to tick in terms of moral lessons about guilt, revenge and (stop me if you’ve heard this one before) “family”. Not to mention regular crash-bang action set pieces. The cartoonish excess is often gratifying, but even when a big CGI fight scene is prefaced with Reynolds saying, “big CGI fight scene coming up”, it is what it is.

The movie’s other major weakness is its continued foregrounding of the white guys at the expense of the consciously inclusive cast around them. Only Brolin’s Cable gets anything resembling a fleshed-out character. Dennison gets some space to make an impression but he’s virtually reprising his Hunt for the Wilderpeople persona, and Deadpool’s bromance with Colossus is the most meaningful relationship in the movie. More problematic is Deadpool’s cool, new African American accomplice Domino, played by Atlanta’s Zazie Beetz (at one point he refers to her as “black black widow”). Her superpower is luck, which gets the plot out of many a corner, but doesn’t extend to the script giving her any decent lines. Baccarin is largely out of the picture, Brianna Hildebrand’s enjoyably snarky Negasonic Teenage Warhead is underused, and her new Japanese girlfriend’s sole personality trait seems to be having purple hair. Worst of all is Karan Soni’s taxi driver Dopinder, a weedy, emasculated Indian stereotype whose superhero aspirations make him the beta-male butt of the joke. Looks as if the writers haven’t got up to speed with The Simpsons’ Apu controversy.

Such concerns might not bother Deadpool 2’s core audience too much, but they implicitly suggest that core audience is white and male, and that everybody else ought to just lighten up. It’s easy to do so, given Reynolds’ undiminished charm, and the generous flow of weapons-grade gags. But now that it’s no longer the underdog, Deadpool is in severe danger of punching down rather than up.